Trough of low pressure will cause isolated heavy rainfall for next two days

What began as light showers on Thursday evening intensified into heavy rain at night in city and suburbs, ending a hiatus in northeast monsoon activity for the past few days.

The trough of low pressure that extends from Sri Lanka to westcentral bay off south coastal Andhra Pradesh across southwest bay off north Tamil Nadu coast is set to bring isolated heavy rainfall over Tamil Nadu and Puducherry for the next two days, according to Meteorological department.

Though it was sunny for few hours in the morning, residents of many areas said wind was strong and often raised dust storm blocking visibility on roads.

The observatories in Nungambakkam and Meenambakkam recorded less than one cm of rainfall between 8.30 a.m. and 5.30 p.m. However, the showers and overcast sky had brought down the day temperature to 29.4 degee Celsius and 29.6 degree Celsius, by three degrees below normal, in both the facilities.

Officials of the Meteorological department said the automatic weather station in Ennore recorded wind speed of 25 km per hour. Whenever there is a drop in surface pressure, it is indicative of active monsoon and strong winds would blow.

Y.E.A.Raj, Deputy Director General of Meteorology, Regional Meteorological Centre, Chennai, said that the city has so far recorded 53 cm of rainfall since October 1. This is deficit by 11 cm for the season. Similarly, Meenambakkam has registered 54 cm of rainfall during the same period, which is less by 4 cm.

However, it is not a cause of worry as the monsoon would withdraw only in the year-end, he said.

It has rained up to 16 cm and 15 cm during November in 2002 and 2009 respectively in a single day. The highest volume of rainfall received during 24 hours was 45 cm on November 25, 1976. This pattern of rainfall may recur this year, he said.

Chennai has already registered 151 cm since January 1, exceeding the annual normal of 140 cm.

This spell of rainfall would continue till Monday and would decrease by December 1, he said. The department forecasts that surface wind would be gusty at times till Saturday.